Euphorbia plant

ABSTRACT

A new variety of Euphorbia plant, being an asexually-reproduced hybrid of Euphorbia lophogona and Euphorbia milii which produces flowers in biaxial ramification, the clusters of which are up to about 15 cm in length, the flowers being yellowish in color and the bracts being up to 32 in number and from salmon pink to luminous salmon red in color, the plant being further characterized by an &#34;ever-blooming&#34; quality, under suitable environmental conditions. Propagation of this new variety is enhanced by control of environment to provide 1000 lux artificial light for a 121/2-hour day at temperatures from 22°-25° C. and humidity 60-90 percent.

This invention relates to a salmon-colored Euphorbia hybrid and methodof vegetative propagation.

The objective of the invention is the production of a uniform Euphorbiahybrid with stable new characteristics, pertaining to a new plantvariety of the Euphorbia genus, as well as method of vegetativepropagation through production of shoots.

In 1970 applicant found (among many thousand Euphorbia plants growing ina cultivated state in the garden of a Catholic mission in Fort Dauphin,Madagascar where a program of controlled breeding was being carried out)an especially striking Euphorbia hybrid with particularly abundantblossoms of luminous salmon-red color which he brought back to develop amarketable container plant for the garden trade. The test results showedthat this Euphorbia hybrid was the result of crossbreeding betweenEuphorbia lophogona, as the mother plant, and Euphorbia milii, as thefather plant.

The applicant has developed, as described hereinafter, a new method ofvegetative propagation through shoot production from the original plantof the new Euphorbia variety and has thus built up a mother-plant stock;from this and pre- and post-selection based on scientific selectionstudies, he finally produced a new Euphorbia variety, more preciselydescribed hereinafter, which in addition to the novel propagation methodis the objective of this patent application.

Since the original plant, with a lifespan of many years duration, doesnot produce shoots under middle European climatic conditions andtemperature range, the applicant undertook numerous experiments wherebyhe exposed the plant to various conditions of artificial lightirradiation at various temperatures and particularly at various degreesof humidity. These tests finally resulted in shoots being produced bythe original plant under the following conditions:

The plants were exposed to an average light intensity of 1000 lux byexposure to artificial light or shade for a 121/2-hour day. They werekept at a temperature of 22°-25° C. and a humidity of 60-90 percentthroughout the experiment.

The applicant thus discovered a new method permitting said Euphorbiahybrid to propagate under European climatic conditions, something thatwas impossible before the advent of this new method. This method canalso be used on other varieties of this species. In any case, thismethod can be used on all Euphorbia varieties which could not bepropagated in middle Europe under normal conditions. In addition, theinvention contemplates that other varieties of Euphorbia plants whichcould not be propagated under middle European conditions can bepropagated by altering the light conditions necessary for vegetativepropagation.

The characteristics and properties of the new Euphorbia variety can bereproduced fully at anytime by using the aforementioned method ofvegetative propagation through production of shoots, however, naturallyoccurring variations resulting from differences in environment have tobe allowed for.

The new Euphorbia variety produced by the aforementioned method, as wellas the method of vegetative propagation, are placed under protection.

The individual characteristics of the new Euphorbia variety aresummarized below; and in the following description the colordescriptions preceded by the initials "RHS-" refer to RoyalHorticultural Society Colour Chart color designations:

Plant: The plant grows in an upright slightly bushy habit, i.e., withascending branches in the lower regions of the main stem; and producesblossoms after reaching a height of about 10 cm. Under appropriateconditions, a new blossom cluster is produced with each leafapproximately every 10-14 days. If the plant is not pruned, it will growapproximately 10-12 cm. per year.

Stem: The stem is grey-green in color, slightly succulent, 1 to 1.5 cmin diameter, with 4 to 5 ridges on which small nodes occur at 2 cmintervals, bearing up to 10 red-brown thorns 0.5 to 2 cm in length. Thusthe stem is of a generally pentagonal cross-section through the thorncluster.

Leaves: The alternately arranged leaves extend almost horizontallyoutward from the stem and branches. The leaves have a short stalk.Ramification from the leaf axis is possible. The leaves are slightlypulpy, dark green (RHS-139A) on the upper side and light green (betweenRHS-139C and RHS-139D) on the underside; they are of varying length andwidth up to about 15 cm in length and up to about 5 cm in width andusually about 3-4 cm in width. The leaves are spatulate, with tipsvarying from very slightly emarginate to very slightly mucronate and anacuminate base. The leaves have a thick middle vein, and short stalk.The thorn clusters are located on nodes on both sides of the leaf axis.A white milky sap exudes from all plant parts when subjected to injury.

Blossoms: A blossom cluster consists of up to 32 single blossoms (eachhaving two salmon-pink to luminous salmon-red bracts) on one pediclewith multiple ramification. Usually, the upper side of the bracts arebluish carmine (RHS-52A) and the underside of the bracts are carminerose (RHS-52D). Discoloration is slight upon light variation. Newblossom clusters arise from each new leaf axis on light green stalks upto 3 mm in thickness and up to about 15 cm in length but usually 5 to 8cm in length. Each blossom cluster is of layered configuration since, asa rule, two new blossoms develop from each individual blossom (biaxialramification). The bracts of an individual blossom surround the flowerorgans and are rounded off, slightly superposed, with a centralindentation and slightly sinous on both sides; they achieve a width ofup to 15 mm. In the appropriate environment, the plant will bloomuninterruptedly. Depending on the temperature and light conditions, thesapling stage of the single blossom has a duration of 8-14 days from theclosed flower-bud to the opening of the bracts (false blossoms) and thesubsequent appearance of the female ovary. The individual blossom isyellowish and dull; the three-part female ovary that appears during thesapling stage, and after 2-4 days, the pollinatable ovary withdraws andthe male blossom organs (stamens) appear. The male stamen grows up to 4mm in height.

The accompanying drawing shows, in color, a plant of the new Euphorbiavariety in full bloom.

I claim:
 1. A hybrid plant of the genus Euphorbia, substantially asherein shown and described and particularly characterized in that it isthe result of crossbreeding between a plant of the Euphorbia lophogonaspecies, as the mother plant, and a plant of the Euphorbia miliispecies, as the father plant, and exhibits the followingcharacteristics: succulent stem with 4 to 5 ridges on which small nodesoccur at 2 cm intervals bearing up to 10 red-brown thorns 2 cm inlength; blossom clusters up to 15 cm in length form at each new leafaxis and bear up to 32 single blossoms each having two salmon pink toluminous salmon red bracts on light green stalks up to 3 mm inthickness; layered configuration of each blossom cluster whereby, as arule, two new blossoms develop from each single blossom; the alternatelyarranged spatulate leaves are slightly pulpy, about 15 cm in length andup to 5 cm in width with a short stalk, said plant being furthercharacterized in that, in the appropriate environment, the plant willbloom uninterruptedly.